1. Technical Field
The present invention relates to a method for manufacturing an organic EL apparatus which is provided with an organic electroluminescence (EL) element, an organic EL apparatus, and an electronic device which is provided with the organic EL apparatus.
2. Related Art
An organic electroluminescent (below, “EL”) element has a configuration where a functional layer which includes an organic light emitting layer is interposed between an anode and a cathode. Holes which are injected from an anode and electrons which are injected from a cathode excite a functional layer by re-bonding and emit fluorescent or phosphorescent light according to the material of the organic light emitting layer.
On the other hand, it is also known that organic EL elements are influenced by moisture or oxygen (below, “moisture or the like”) from outside. In a case where moisture or the like enters an organic EL element, for example, the state of the interface between both electrodes and the functional layer changes and it is not possible to efficiently transport the holes or electrons to the functional layer and, as a result, so-called dark spots where it is not possible to obtain a desired brightness in an organic light emitting layer may be generated. That is, in the organic EL element, a sealing technique for excluding the influence of moisture or the like is extremely important and several countermeasures therefor have been employed up to now.
For example, a “thin film sealing method” in which the organic EL element is covered with a sealing film with high gas barrier properties with respect to moisture or the like has been proposed. In the thin film sealing method, the gas barrier properties are secured with respect to the moisture or the like by forming a sealing film in a region where an organic EL element is formed. Then, normally, since a mounting electrode for creating conduction between the organic EL element and outside is also already formed in a phase before the sealing film is formed, there are cases where the sealing film also overlaps the mounting terminal. Therefore, a method in which a mounting terminal is masked with a metal mask or the like in advance is adopted.
In a case of using a metal mask, variations are generated in the film thickness of the sealing film, caused by limits on the incidence of forming particles of the sealing film in the periphery of an opening section of the metal mask, the sealing film wrapping around directly under an end section of the opening section of the metal mask, or the like. Thus, in order to reliably cover the organic EL element with the sealing film, it is necessary to widely secure an interval between the opening section of the metal mask and the organic EL element to a certain extent, which is also a factor inhibiting the miniaturization of the organic EL apparatus.
As a method which solves such a problem, JP-A-2007-234610 discloses a method in which, after forming a protective film in an organic EL element, a protective film which overlaps an external connecting region which includes an external connecting terminal is anisotropically etched while using a sealing substrate of a display apparatus, which is provided with the organic EL element, as a mask. According to this method, it is possible to expose the external connecting region by selectively removing a protective film along a vertical surface which includes an end surface of the sealing substrate.
However, according to JP-A-2007-234610 described above, since a sealing substrate is used as a mask, the sealing substrate is also etched to no small extent. For example, in a case of using blue sheet glass, non-alkali glass, or the like for the sealing substrate, a component (for example, Al, Ca, or the like or oxides thereof) other than silicon oxide (SiO) which is included in the glass remains without being removed as a reaction product during etching. Then, there is a concern that these residues will be re-attached to the external connecting terminal after removing the protective film. Thus, in a process which is performed later and in which electrical connection between the external connecting terminal and an external circuit is obtained, the connection reliability deteriorates due to the connection strength being reduced and problems also occur in which the electrical characteristics cannot be secured.